Rheumatoid arthritis (RA) and osteoarthritis (OA) are highly prevalent and have reached epidemic proportions in the US and worldwide. These joint diseases are characterized by inflammation, swelling (particularly in RA), pain, and limited mobility. Despite significant advances in developing anti-inflammatory therapies, biologics, and symptomatic pain relief measures, significant shortcomings in treating these diseases remain, buttressing the need for robust research to meet this urgent health predicament. A wide range of small animal models of joint disease, including RA and OA, has been developed in recent years and helped advance our understanding of disease pathology, underlying mechanisms, disease management and therapeutic intervention. However, the reproducible implementation of these models is challenging, especially in the hands of non-experts and due to scarcity of validated benchmark criteria across studies. At the same time, tests of animal behavior, sensitivity, and musculoskeletal function have demonstrated value in identifying symptoms and joint dysfunction in rodent models of arthritis. Yet, the full spectrum of creation of joint injury/disease models and evaluation of functional outcomes to achieve comprehensive analysis is rarely used by most research groups due to limited availability of essential resources. Core D will address this need by supporting model implementation and functional assessment as an integrated resource. Our ability to do so rests on the collective expertise of the Core leaders in inflammatory joint disease (Dr. Abu-Amer), post-traumatic OA (Drs. O?Keefe and Shen) and functional assessment of joint pain and dysfunction (Drs. Guilak and Setton). Notably, four of these investigators joined the WUSTL Research Community in the past few years, which has provided our Center with a unique opportunity to develop this Resource Core. Our goal is to advance current knowledge to bridge gaps in our understanding of the cellular, molecular and functional basis of joint arthritis, and to develop and evaluate new therapeutic strategies. The Core will standardize protocols and support the reproducible implementation of RA and OA models for widespread use by the Research Community. We will facilitate collaboration with Cores B and C to enable comprehensive analyses. Importantly, the Core will organize critical resources, including a facility for testing murine musculoskeletal function and behavior. We will establish a new, organized biomaterial resource to collect and store tissue and serum samples from RA and OA mouse models, which will be made available as a standard resource for histology, gene and protein screens by all investigators. Finally, the Core will provide hands-on training and enrichment program to train the next generation of joint investigators. Our Specific Aims are: Aim 1: Support the implementation and utilization of reproducible OA and RA mouse models. Aim 2: Provide measures of biomechanics, behavior, and function to assess mouse joint function. Aim 3: Establish murine OA and RA biomaterials repository. Aim 4: Provide hands-on training, outreach and enrichment.